1. Field of the Invention
The present invention relates to an apparatus for the continuous separation of solids from a liquid suspension thereof and, more particularly, to a continuously operating powdered resin-water slurry separator which will separate essentially all of the resin as a concentrated fraction of the slurry, with the other fraction thereof being the balance of the water contained in the original feed slurry.
Generally, the invention relates to an apparatus or separator for continuously separating a powdered resin material, such as finely-divided high-density polyethylene particles, which is suspended in water and supplied to the separator as an infeed slurry, by permitting the resin, which is of a lower specific gravity than the water, to float upwardly within a vessel from whence it is withdrawn as a thickened slurry through an outlet orifice located in the upper portion of the vessel. The infeed slurry is fed into the lower central section of the vessel, and an outlet orifice for the clarified liquid or water is provided in the vessel proximate the base portion thereof.
Although numerous apparatuses and processes are currently known and in industrial use for the continuous or batchwise separation of solids which are suspended in liquid to thereby form a slurry, and wherein the solids are permitted to float gravitationally upwardly within a vessel or upright tank by being of a lower specific gravity than the liquid, the current state of the technology fails to provide structure which will effect the separation in a manner as efficiently and economically as that contemplated and attained by the present inventive liquid-solids separator.
2. Discussion of the Prior Art
Thus, Fontein U.S. Pat. No. 2,649,963 discloses a continuously operating separator for processing and continuously thickening or concentrating slurries of finely-divided solids suspended in a liquid media, in which an upwardly-reducing conical vessel has a slurry fed into the lower portion thereof, allowing the dispersed solids to float upwardly and form a thickened slurry, and with the fraction comprising relatively pure or clarified liquid being removed from proximate the bottom of the apparatus. The more concentrated suspension or thickened slurry is withdrawn from the upper end of the conical vessel through the intermediary of a vortex-type blower arrangement.
Lessing et al U.S. Pat. No. 1,989,937 discloses an apparatus for the separation from a liquid of a carbonaceous material suspended therein to form a slurry, in which particles having a specific gravity lower than that of the liquid will float to the top surface and will be skimmed off through the utilization of a conveyor system, with the purer or clarified liquid being allowed to flow out through an orifice provided in the bottom of a receptacle or vessel constituting the apparatus.
Grundler U.S. Pat. No. 1,169,479 and Walter U.S. Pat. No. 2,220,925 show separators for the separation of substances having different specific gravities, in particular particulate material entrained and suspended in a liquid forming a slurry, by incorporating stirring devices which will uniformly disperse the solids material in the slurry at the upper end of the apparatus in which the slurry is more concentrated, thereby imparting a constant consistency to the slurry.
Holz et al U.S. Pat. No. 3,964,996 discloses an apparatus for the separation of solids from a liquid suspension thereof, having a central feed slurry inlet provided in a vessel, in which fibrous suspension material of lower specific gravity than the liquid is allowed to float upwardly under the effect of gravity and withdrawn from the upper end of the apparatus, with the more pure or clarified liquid being withdrawn from the lower portion of the apparatus.
Although these and other publications each disclose and relate to various apparatuses and methods of processing slurries through the separating of solids from liquid suspensions, essentially through the application of the flotation principle in which the solids are of a specific gravity lower than that of the liquid in which they are entrained, none facilitate an economical operation analogous to that of the inventive apparatus, the latter of which incorporates novel anti-swirl baffles in the upper regions of the separator vessel which will prevent undue agitation of the solid material as it floats upwardly, due to infeed and convection currents; which incorporates a stilling baffle or screen extending across the lower portion of the separator in order to prevent any solids particles from being withdrawn through an outlet provided in the lower region of the separator for the purer or clarified slurry liquid; and which also incorporates means for imparting agitation to the thickened slurry proximate an outlet therefor arranged in the upper region of the separator in order to maintain the accumulated resin or solids particulate material in the slurry uniformly dispersed throughout the liquid in which it is suspended as the thickened slurry is being withdrawn from the separator.